Add TODOs for broken build code in aggregate_vector_icons.

ui/gfx/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 551 matching lines @@
     "vector_icons/zoom_minus.icon",
     "vector_icons/zoom_plus.icon",
   ]
 
   outputs = [
     vector_icons_cc_file,
     vector_icons_h_file,
   ]
 
   args = [
+    # TODO(brettw) bug 535386: This should not take a directory as an input,
+    # but rather a response file listing the inputs or sometimes the build will
+    # be incorrect. In this case, Ninja won't be able to do proper dependency
+    # tracking since if a file is deleted, the command line will be the same
+    # and the action will not be re-run.
     "--working_directory=" + rebase_path("vector_icons/"),
     "--output_cc=" + rebase_path(vector_icons_cc_file, root_build_dir),
     "--output_h=" + rebase_path(vector_icons_h_file, root_build_dir),
   ]
 }
 
 # Looking for gfx_geometry? It's //ui/gfx/geometry:geometry
 
 source_set("test_support") {
   testonly = true
@@ skipping 197 matching lines @@
 if (is_android) {
   generate_jni("gfx_jni_headers") {
     sources = [
       "../android/java/src/org/chromium/ui/gfx/BitmapHelper.java",
       "../android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java",
       "../android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java",
     ]
     jni_package = "gfx"
   }
 }